Star Formation Rate and Environment in the SDSS-DR4

Abstract

We investigate the environmental dependence of galaxies with the star formation rate (SFR) in a complete volume limited sample of 91566 galaxies, in the redshift range $0.05\le z\le 0.095$, and with $M_r=-20.0$ (that is M${}^{\ast }$ + 1.45), selected from the Sloan Digital Sky Survey Data Release 4 (SDSS-DR4). The environment is characterized by the local number density of galaxies, defined by the parameter ${\Sigma }_N(\frac{N}{\pi \ast r_N^2})$, with N=5. We find a reletaion between the distance of the nearest neighbour and the SFR, and confirm the general trend for the SFR of decreasesing with increasing density.

Published in the Proceedings of the "I Workshop of Astronomy and Astrophysics for Students", Eds. N.R. Napolitano & M. Paolillo, Naples, 19-20 April 2006 (astro-ph/0701577)